Axiom Home Page Forums General Discussion Technical Questions Bass/Rumble from EP500v2 with no audio input

Greetings all!

I received a replacement amp for my EP500v2 which was previously making a static or "snow" noise with no audio input and didn't really produce bass correctly with an audio input - just the noise. I replaced the old amp with the new one and now it's silent (well, sometimes) for a few moments and then creates a bass/rumble that grows over a period of time - also with no audio input. To me it feels kinda like hearing a train slowly approaching. I've tried different power cables, different circuits, cheater plugs, removing the ground chassis screw etc. with no success. Changing the crossover or trim may change the intensity of the "rumble" but doesn't make it disappear (changing the volume either makes it worse or has no effect). I've tried the 12volt test on the driver itself and that appears to work just fine.

Anybody have ideas/suggestions? Could it be the driver that's actually gone bad (which doesn't make any sense to me)? I've emailed Brent to see what he'd like me to do as well. After spending a lot of time trying to trouble-shoot the first issue and figuring the amp went bad I'm rather at a loss on this.

Hi,

So are you saying if you just plug the sub power in and have all other wires disconnected (ie RCA) the sub makes this rumble noise?

If this noise is made with the rca plug , plugged in then I would say to try a better cable. I had a similar situation , where I had grabbed a set of rca cables that had been in my sons car. They worked fine for a few months then one day I noticed some odd rumblings, long story short I changed to better and shorter cables and problem solved. Sub amps are sensitive and any inductance in the wire will be reproduced.

I'd be looking at the cables as well, perhaps the 1/4->RCA adapter plug (if you've got one with that). That's where I get that sort of thing happening with my EP350.

That's correct - I currently only have power going to the sub and I get the rumble noise. Adding the RCA cable just makes it worse (with added hum I think)

I have a different RCA cable from Axiom as well... but since it happens without the RCA cable connected to the sub I think I need to get the rumble corrected first.

Thanks guys!

and actually, connecting the RCA cable to the sub (without it connected to the receiver) makes it hum like crazy.

Call Axiom.

if you are touching the ends it will hum, we all have some electric current. My mom couldn't wear a watch, they would die a sad death. New cables are not that expensive, wortha shot

Yeah, dang. I'll wait to hear back from Brent then. Thanks again!

Nope, not touching the ends of the cables either

My ep500 never did work quite right from the time I bought it used. I gave up on using the line-level input, which made lots of noise regardless of any input signal, and now I just use the high-level inputs. So that might be something to try. (Now, the volume on mine is drifting upwards -- I have it set at 0, else it's too loud.)

If you unplug the main AC cord for a few minutes and then plug it back in does the occasional rumbling (like thunder off in the distance) go away? If so, how long does it go away. If many days/wks, then sounds like the same problem others including me have had in the past. For some reason the amp stores up a charge and unplugging it releases it, did they send you a refurbed amp?

People just forget about MarkSJohnson's movie production at my place.

Actually, if I remember correctly it does seem like it goes away (for a brief moment anyways). If I unplug it and plug it back in the rumblings happen fairly quickly - if I took a while (switching outlets or whatnot) it may take 15-30 seconds before the rumbling happens. The crazy hum though will happen as soon as I touch the input regardless of how long it was unplugged - and you're correct, I got a refurbished amp.

Brent had me try just using the High-Level input - no such luck unfortunately. Did find out that adjusting the crossover setting on the sub does affect the "loudness" of the rumblings though (40 - pretty quiet, as you turn it higher the crazier the rumblings become)... and yeah, really does kinda seem like a charge is building up. Left Axiom a message as well with my number

*waits patiently*

How close is the sub to your towers?
I read a review about an axiom sub and an axiom tower reacting to each other.
I don't understand how its possible.

They're a good 10ft apart (towers in the front, sub is behind/next to the couch).

Brent is going to have me send it back for them to take a look at it - appears there really isn't anything else for me to check at this point! Can't wait to send it back in... then I'll be eagerly awaiting for it to return heh

I had an ep500 once that was acting strage. When the gain was set low you could not hear it, but as you gradually increased the gain all of a sudden it would jump like 20dBs. I found if I pushed with my fingers around the amp plate near the gain nob I could recreate the problem. They ended up replacing the amp.

Interesting, didn't think about trying to press around anything on the back of the AMP. I believe the AMP should have reached them in NY early this morning